Process of making lead carbonates.



UNITED STATES PATENT OFFICE.

PROCESS ,QF MAKING LEAD CARBONATES.

Specification of Letters Patent.

Patented Sept. 19, 1905.

Application filed April 5,1905. Serial No. 254,038.

To all whom it may concern:

Be it known that I, ADOLF WULTZE, chemist, a subject of the King of Prussia, German Emperor, and a resident of Charlottenburg, near Berlin, Kingdom of Prussia, German Empire, have invented a new and useful Process of Manufacturing Lead Carbonates, of which the following is an exact specification.

The subject of the present invention consists in the manufacture of neutral or basic lead carbonates by treating solutions of lead acetate with carbonic acid, so as to be suitable to serve as white coloring-matter.

If carbonic acid is introduced into a diluted solution of sugar of lead, a precipitation of crystalline lead carbonate arises which contains about sixteen per cent. of carbonic acid. If carbonic acid is introduced into a diluted basic solution of sugar of lead, a precipitation of basic lead carbonate containing about thirteen to fourteen per cent. of carbonic acid is obtained. Furthermore, if carbonic acid is introduced under an increased pressure into a diluted solution of sugar of lead also a precipitation of neutral carbonate containing about sixteen per cent. of carbonic acid arises. A neutral lead carbonate with about sixteen per cent. of carbonic acid is in a striking manner also obtained when carbonic acid isintroduced under a higher pressure into a basic lead vinegar. All the carbonates so obtained are more or less coarse crystalline and are not suitable to serve as coloring-matter on want of every covering and illuminating power.

1 have now found that the height of the pressure and the basicity of the lead solution are of little importance, but that for obtaining a certain physical state which is condition for the lead carbonates being-suitable as coloring-matter the manner is decisive in which the carbonic acid comes in contact with the solutions of the lead acetates. I have asserted that if at the precipitation the carbonic acid is brought within a very short time-for instance, part of a secoudin contact with the liquid to be precipitated upon a higher pressure the formation of a coarse crystalline precipitation is excluded and lead carbonates arise which surpass with regard to their white color and covering power the best kinds on the market. Such a precipitation arises with the basic as in the solution of acetate is contained is suddenly connected to a reservoir in which the manifold quantity of carbonic acid is contained under a pressure of three to four atmospheres. In all cases the precipitation is then efiected in so short a time that a perfect amorphous highly-covering carbonate is obtained. It is already mentioned above that according to the obtained from neutral as well as from basic solutions of acetate. It is possible with the present process to obtain at will, according to the requirements of the market, neutral or basic carbonate from basic acetic solutions of lead. To obtain basic or neutral carbonate depends thereon whether the carbonic acid is introduced to that point where the basic sugar of lead is neutral or begins to become somewhat acetic or whether the carbonic acid is allowed to act to such a degree that any precipitation does no more take place from the solution. In the latter case the freed acetic acid seems to dissolve the precipitated hydroxid under forming back the solution of sugar of lead, wherefrom the neutral carbonate is then formed. Furthermore, it can be also obtained at will to manufacture, according to the requirements of the market, heavy or light white lead by employing stronger or thinner solutions, which equally behave with regard to the white color and covering power of the product obtained. My experiments have proved that such qualities of White lead could hitherto not be obtained by any of the known methods of manufacturing.

Having thus fully described the nature of this invention, whatIdesire to secure by Letters Patent of the United States is Process for manufacturing lead carbonate consisting in acting of carbonic acid upon lead process indicated these precipitations can be acetates and producing at the same-time a r In witness whereof time hereunto set my sudden overpressure being at least one atmoshand in the presence of two Witnesses. phere at the place of precipitating the lead carbonate, whereby the latter is precipitated ADOLF WULTZE' 5 within a very short time and suddenly, thereby Witnesses:

preventing the precipitation from becoming HENRY HASPER,

crystalline, substantially as described. WOLDEMAR HAUPT. 

